Temporary intraluminal filter guidewire

ABSTRACT

The present invention is a temporary intraluminal filter guidewire for use during interventional procedures, such as angioplasty or stent deployment. A braided filter is mounted near the distal end of a steerable guidewire, which guides a therapeutic catheter. An actuator rod slides over the guidewire and is removably connected to the filter. The rod controls relative displacement of the filter ends, causing transformation of the filter between a deployed configuration and a collapsed configuration. In several embodiments, the guidewire distal to the filter has a fixed tip length. Other embodiments of the invention include a mechanism for damping longitudinal movement between the distal and proximal ends of the filter.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 09/824,832 to Douk et al. filed Apr. 3, 2001 nowpending entitled “Temporary Intraluminal Filter Guidewire and Methods ofUse.”

FIELD OF THE INVENTION

The present invention relates generally to intraluminal devices forcapturing particulate in the vessels of a patient. More particularly,the invention relates to a filter for capturing emboli in a blood vesselduring an interventional vascular procedure and then removing thecaptured emboli from the patient after completion of the procedure.Furthermore, the invention concerns a filter mounted on a guidewire thatcan also be used to direct an interventional catheter to a treatmentsite within a patient.

BACKGROUND OF THE INVENTION

A variety of treatments exists for dilating or removing atheroscleroticplaque in blood vessels. The use of an angioplasty balloon catheter iscommon in the art as a minimally invasive treatment to enlarge astenotic or diseased blood vessel. When applied to the vessels of theheart, this treatment is known as percutaneous transluminal coronaryangioplasty, or PTCA. To provide radial support to the treated vessel inorder to prolong the positive effects of PTCA, a stent may be implantedin conjunction with the procedure.

Thrombectomy is a minimally invasive technique for removal of an entirethrombosis or a sufficient portion of the thrombosis to enlarge thestenotic or diseased blood vessel and may be accomplished instead of aPTCA procedure. Atherectomy is another well known minimally invasiveprocedure that mechanically cuts or abrades a stenosis within thediseased portion of the vessel. Alternatively, ablation therapies uselaser or RF signals to superheat or vaporize the thrombus within thevessel. Emboli loosened during such procedures may be removed from thepatient through the catheter.

During each of these procedures, there is a risk that emboli dislodgedby the procedure will migrate through the circulatory system and causeinfarction or strokes. Thus, practitioners have approached prevention ofescaped emboli through use of occlusion devices, filters, lysing andaspiration techniques. For example, it is known to remove the embolicmaterial by suction through an aspiration lumen in the treatmentcatheter or by capturing emboli in a filter or occlusion devicepositioned distal of the treatment area.

Prior art temporary filters or occlusion devices are associated witheither a catheter or guidewire and are positioned downstream of the areato be treated. One prior art filter arrangement includes a dilatationballoon and a filter mounted on the same catheter. The filter is locateddistal to the dilatation balloon and consists of a filter materialsecured to resilient ribs. A filter balloon is located between thecatheter exterior and the ribs. Inflation of the filter balloon extendsthe ribs outward across the vessel to form a trap for fragments loosenedby the dilatation balloon. When the filter balloon is deflated, theresilient ribs retract against the catheter to retain the fragmentsduring withdrawal of the catheter.

Another prior art device includes a filter mounted on the distal portionof a hollow guidewire or tube. A moveable core wire is used to open andclose the filter. The filter is secured at the proximal end to the tubeand at the distal end to the core wire. Pulling on the core wire whilepushing on the tube draws the ends of the filter toward each other,causing the filter framework between the ends to expand outward intocontact with the vessel wall. Filter mesh material is mounted to thefilter framework. To collapse the filter, the procedure is reversed;pulling on the tube while pushing on the core wire to draw the filterends apart.

Another prior art device has a filter made from a shape memory material.The device is deployed by moving the proximal end of the filter towardsthe distal end. It is collapsed and withdrawn by sliding a sheath overthe filter and then removing the sheath and filter together.

A further prior art filter device discloses a compressible polymericfoam filter mounted on a shaft that is inserted over a guidewire. Thefilter is inserted collapsed within a housing which is removed to deploythe filter once in position. The filter is retracted by inserting alarge bore catheter over the shaft and the filter, and then removing theshaft, filter and catheter together.

Another prior art filter arrangement has a filter comprised of a distalfilter material secured to a proximal framework. This filter is deployedin an umbrella manner with a proximal member sliding along the shaftdistally to open the filter and proximally to retract the filter. Alarge separate filter sheath can be slid onto the shaft and the filteris withdrawn into the sheath for removal from the patient.

Other known prior art filters are secured to the distal end of aguidewire with a tubular shaft. Stoppers are placed on the guidewireproximal and distal of the filter, allowing the filter to move axiallyindependently of the guidewire. A sheath is used to deploy and compressthe filter.

However, the guidewire-based filter devices do not have the handlingcharacteristics expected of steerable guidewires. Abrupt transitions instiffness in the area of the filter can limit the ability of theguidewire to negotiate tortuous vascular anatomy. Such devicelimitations can restrict the number of patients receiving the benefitsof filtration during interventional vascular procedures. Filterguidewires that use a moveable core wire to actuate the filter also havediminished performance characteristics.

Another problem associated with prior art filter guidewires is therequirement for a sheath to envelop and collapse the filter before andafter the treatment is performed. Sheaths that encase the filter oftenrequire large bores, with attendant bulky handling. It is time-consumingand cumbersome to exchange the sheath for the treatment catheter and toreverse this exchange step at the end of the procedure.

Another problem associated with self-expanding temporary filters isvisualization of the filter under fluoroscopy. Filter braiding materialshaving good mechanical properties are not also very radiopaque to X-raystypically used during clinical procedures. Solutions to this problemtypically require the addition of radiopaque material to the braidingwires, which often diminishes their shape-memory or elastic properties,or both.

With the above in mind, it is an object of the present invention toprovide a filter guidewire with improved handling characteristics.

Another object of the present invention is to provide a filter guidewirethat does not require an enveloping sheath to collapse the filter forinsertion or withdrawal.

Another object of the invention is to provide a radiopaque temporaryfilter with undiminished physical performance.

BRIEF SUMMARY OF THE INVENTION

The present invention is a temporary filter guidewire for use inintraluminal procedures. The device includes a filter assembly mountedadjacent the distal end of a guidewire used in the procedure. The filteris a tubular assembly that expands in the middle region when the endsare drawn toward each other. The filter assembly includes an expandableframe with a distal portion acting as the emboli filter. The embolifilter is sized sufficiently to expand and cover the lumen of the vesseldistal to the intended treatment area.

In one embodiment of the invention, the guidewire includes a moveablecore wire having a tapered distal end to which the distal end of thefilter is attached. The proximal end of the filter is attached to thedistal end of a guidewire tubular shaft. The guidewire shaft includes astiff, elongate proximal portion for steering and transmitting axialforce, and a relatively flexible distal portion for negotiating tortuousvascular anatomy. A transition sleeve is fixed to the core wire and fitsslidingly inside the distal end of the tubular shaft. The sleeve extendsdistal to the shaft, providing a smooth transition in stiffness where anabrupt change would otherwise occur. The combination of tapered corewire, flexible distal shaft region and transition sleeve results in afilter guidewire with handling characteristics that are comparable tostandard steerable guidewires.

A second embodiment of the invention is built around a standard-typesteerable guidewire, which includes an elongate shaft having a distalregion surrounded by a flexible tubular element, such as a coiledspring. Both the proximal and distal ends of a self-expanding tubularfilter assembly are slidably mounted adjacent the distal end of theguidewire, with a stop element fixed to the guidewire between the filterends to limit axial movement thereof. Mounted to the proximal end of thefilter is a sliding actuator, which is selectively engageable with ahollow rod slidably disposed over the guidewire. Proximally directedforce can be applied to the filter proximal end by pulling thecombination of the rod and the actuator while pushing the guidewiredistally. A first degree of such proximally directed force will collapsethe filter by separating the filter proximal end from the filter distalend, which is restrained against proximal movement by the stop element.A second, higher degree of proximally directed force will disengage therod from the actuator, permitting the rod to be withdrawn from thepatient and allowing the filter to self-expand. In several alternativeversions of the second embodiment, a damping mechanism slows theself-expansion of the filter to prevent possible sudden impact of thefilter against the wall of the vessel being treated.

In a third embodiment of the invention, a tubular filter assembly ismounted adjacent the distal end of a standard-type steerable guidewire,which is described above. The distal end of the filter is slidablymounted to the guidewire, and the proximal end is fixed thereto. Anactuator mechanism includes a link element slidably extending throughthe proximal end of the filter to provide a mechanical connectionbetween the distal end of the filter and a proximal tubular controlelement. In this embodiment of the invention, the actuator mechanismreverses the push-pull action used for transforming the filter betweencollapsed and deployed configurations in the prior art and in the firstand second embodiments of the invention. Thus, pulling on the guidewireand pushing on the tubular control element causes the filter to becollapsed, rather than deployed. In the third embodiment of theinvention, the actuator is an elongate hollow rod slidably mounted overthe guidewire. The rod can be manipulated directly from the proximal endof the device. The fourth embodiment of the invention is similar to thethird embodiment, except that the actuator is a relatively short ring,which is operable by a removable hollow rod or tube, which may comprisea therapeutic catheter.

A fifth embodiment of the invention resembles the fourth embodiment,except that both the proximal and distal ends of the filter are fixed tothe guidewire, which is separated into two sections that are slidablewith respect to each other during transformation of the filter betweencollapsed and open configurations. This embodiment provides theadvantageous “reversed” push-pull actuation of the third and fourthembodiments with a desirable fixed tip length feature that is providedby the first embodiment.

To provide a temporary filter with enhanced radiopacity, but withundiminished physical performance, radiopaque material is added to oneor more braiding wires, in the centers thereof, where the effect onphysical properties of the wires is minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is an illustration of a filter system in accordance with theinvention deployed within a blood vessel;

FIG. 2 is an illustration of a filter system in accordance with theinvention deployed within a portion of the coronary arterial anatomy;

FIG. 3 is an illustration of a prior art expandable mesh device, shownwith the mesh in a collapsed configuration;

FIG. 4 is an illustration of a prior art expandable mesh device, shownwith the mesh in a deployed configuration;

FIG. 5 is a longitudinal sectional view of a first guidewire filterembodiment in accordance with the invention;

FIG. 6 is a longitudinal sectional view of a second guidewire filterembodiment in accordance with the invention;

FIGS. 7-10 are illustrations of alternative actuators usable with thesecond guidewire filter embodiment in accordance with the invention;

FIG. 11 is a longitudinal sectional view of a third guidewire filterembodiment in accordance with the invention;

FIG. 12 is a longitudinal sectional view of a fourth guidewire filterembodiment in accordance with the invention, including a hollow rodslidably positioned thereon;

FIG. 13 is a longitudinal view of the fourth guidewire filter systemembodiment in accordance with the invention, including a ballooncatheter slidably positioned thereon, shown with the filter in adeployed configuration;

FIG. 14 is a longitudinal view of the fourth guidewire filter systemembodiment in accordance with the invention, including a ballooncatheter slidably positioned thereon, shown with the filter in acollapsed configuration;

FIG. 15 is a side view taken of the distal portion of another guidewirefilter system in accordance with the invention, showing a proximalassist spring;

FIG. 16 is a side view taken of the distal portion of another guidewirefilter system in accordance with the invention, showing a distal assistspring;

FIG. 17 is a partial longitudinal sectional view taken of the distalportion of another guidewire filter system in accordance with theinvention, showing an assist spring inside the filter;

FIGS. 18 and 20 are flow charts depicting methods of using the guidewirefilter system of the present invention;

FIG. 19 is a side view of an alternative embodiment of a hollow rod foractuating guidewire filters in accordance with the second, fourth andfifth embodiments of the invention;

FIG. 21 is a longitudinal partial section of a portion of enhancedradiopacity wire used in making a filter in accordance with theinvention;

FIG. 22 is a transverse sectional view of enhanced radiopacity wire usedin making a filter in accordance with the invention taken along the line22—22 of FIG. 21;

FIG. 23 is a portion of a braided filter in accordance with theinvention, with portions of enhanced radiopacity braiding wire exposed;

FIG. 24 is a longitudinal sectional view of a fifth guidewire filterembodiment in accordance with the invention, including a hollow rodslidably positioned thereon;

FIG. 25 is a longitudinal sectional view of an alternative version ofthe fifth guidewire filter embodiment in accordance with the invention;

FIG. 26 is a longitudinal sectional view of another alternative versionof the fifth guidewire filter embodiment in accordance with theinvention;

FIG. 27 is a longitudinal sectional view of an alternative version ofthe second guidewire filter embodiment in accordance with the invention,including a hollow rod slidably positioned thereon;

FIG. 28 is a longitudinal sectional view of another alternative versionof the second guidewire filter embodiment in accordance with theinvention, including a hollow rod slidably positioned thereon; and

FIG. 29 is a longitudinal sectional view of yet another alternativeversion of the second guidewire filter embodiment in accordance with theinvention, including a hollow rod slidably positioned thereon.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a temporary filter guidewire for use inminimally invasive procedures, such as vascular interventions or otherprocedures where the practitioner desires to capture embolic materialthat may be dislodged during the procedure. Intravascular proceduressuch as PTCA or stent deployment are often preferable to more invasivesurgical techniques in the treatment of vascular narrowings, calledstenoses or lesions. With reference to FIG. 1 and FIG. 2, deployment ofballoon expandable stent 5 is accomplished by threading catheter 10through the vascular system of the patient until stent 5 is locatedwithin a stenosis at predetermined treatment site 15. Once positioned,balloon 11 of catheter 10 is inflated to expand stent 5 against thevascular wall to maintain the opening. Stent deployment can be performedfollowing treatments such as angioplasty, or during initial balloondilation of the treatment site, which is referred to as primarystenting.

Catheter 10 is typically guided to treatment site 15 by a guidewire. Incases where the target stenosis is located in tortuous vessels that areremote from the vascular access point, such as coronary arteries 17shown in FIG. 2, a steerable guidewire is commonly used.

According to the present invention, filter guidewire generallydesignated as 20 guides catheter 10 to treatment site 15 and includesdistally disposed filter 25 to collect embolic debris that may begenerated during the procedure. The invention is directed tomanipulating various types of temporary filters wherein relativemovement of the filter ends either causes or accompanies transformationof the filter between a collapsed configuration and an open, or deployedconfiguration. Such transformation may be impelled by externalmechanical means or by self-shaping memory (either self-expanding orself-collapsing) within the filter itself. Preferably, filter 25 isself-expanding, meaning that filter 25 has a mechanical memory to returnto the expanded, or deployed configuration. Such mechanical memory canbe imparted to the metal comprising filter 25 by thermal treatment toachieve a spring temper in stainless steel, for example, or to set ashape memory in a susceptible metal alloy such as a binarynickel-titanium (nitinol) alloy. Filter 25 preferably comprises a tubeformed by braided filaments that define pores and have at least oneinlet opening 66 that is substantially larger than the pores.Alternative types of filters may be used in filter 25, such as filterassemblies that include a porous mesh mounted to expandable struts.

Optionally, adding radiopaque markers (not shown) to filter ends 27, 29can aid in fluoroscopic observation of filter 25 during manipulationthereof. Alternatively, to enhance visualization of braided filter 25under fluoroscopy, at least one of the filaments may be a wire havingenhanced radiopacity compared to conventional non-radiopaque wiressuitable for braiding filter 25. At least the majority of braiding wiresforming filter 25 should be capable of being heat set into the desiredfilter shape, and such wires should also have sufficient elasticproperties to provide the desired self-opening or self-collapsingfeatures. Stainless steel, and preferably nitinol monofilaments aresuitable for braiding filter 25. A braiding wire having enhancedradiopacity may be made of, or coated with, a radiopaque metal such asgold, platinum, tungsten, alloys thereof, or other biocompatible metalshaving a relatively high X-ray attenuation coefficient compared withstainless steel or nitinol. One or more filaments having enhancedradiopacity may be inter-woven with non-radiopaque wires, or all wirescomprising filter 25 may have the same enhanced radiopacity.

Alternatively, as shown in FIGS. 21-23, one or more of the braidfilaments may comprise composite wire 24, having radiopaque core 26 andnon-radiopaque layer or casing 28. Such coaxial, composite wires arereferred to as DFT (drawn-filled-tube) wires in the metallic arts, andare formed by inserting a solid billet of one metal into a hollow billetof a different metal, then repeatedly drawing and annealing thecombination until a wire of desired diameter and hardness is achieved. Apreferred DFT wire for use in the instant invention comprises a core ofa 90% platinum-10% nickel alloy, and a casing of binary nickel-titanium(nitinol (NiTi) alloy. By placing the more radiopaque, but more ductilematerial in the center of wire 24, the nitinol outer layer is able toprovide the resulting wire with nearly undiminished mechanicalproperties, as compared with nitinol wire alone. Conversely, placing aradiopaque coating or layer around a nitinol core substantially effectsthe physical properties of the wire. Thus, in comparison to nitinolmonofilament wire, PtNi core/nitinol tube DFT wire has a greater X-rayattenuation coefficient and nearly identical mechanical properties. Wire24, comprising a PtNi core/nitinol tube combination, provides improvedradiopacity of filter 25 without giving up the shape-memory orpseudo-elastic properties of nitinol, which contribute to goodshape-retention and the elastic transformation of filter 25 betweencollapsed and deployed configurations. In the preferred DFT combinationof wire 24, core 26 makes up at least approximately 25% of the totalcross-section of wire 24, by area. In making filter 25 in a sizeintended for use in vessels up to about 6 mm in diameter, wire 24 ispreferably about 0.001-0.003 inch (0.03-0.08 mm) diameter, morepreferably about 0.002 inch (0.05 mm) diameter. Such wires are availablefrom Fort Wayne Metals Corp., Fort Wayne, Ind., U.S.A.

In accordance with the invention, maintaining filter 25 in a collapsedconfiguration during introduction and withdrawal of filter guidewire 20does not require a control sheath that slidingly envelops filter 25.Thus, this type of device is sometimes termed “sheathless.” Known typesof sheathless vascular filter devices are operated by a “push-pull”mechanism that is also typical of other expandable braid devices, asshown in FIGS. 3 and 4. Prior art expandable braid device 30 includescore wire 32 and tubular shaft 34 slidably disposed there about. Tubularbraid 36 surrounds core wire 32 and has a braid distal end fixed to corewire distal end 40 and a braid proximal end fixed to shaft distal end41. To expand braid 36, core wire 32 is pulled and shaft 34 is pushed,as shown by arrows 37 and 39 respectively in FIG. 4. The relativedisplacement of core wire 32 and shaft 34 moves the ends of braid 36towards each other, forcing the middle region of braid 36 to expand. Tocollapse braid 36, core wire 32 is pushed and shaft 34 is pulled, asshown by arrows 33 and 35 respectively in FIG. 3. This reversemanipulation draws the ends of braid 36 apart, pulling the middle regionof braid 36 radially inward toward core wire 32.

Referring now to FIG. 5, in a first embodiment of the invention, filterguidewire 20 includes core wire 42 and flexible tubular tip member 43,which is preferably a coil spring, fixed around the distal end of corewire 42. Thin wires made from stainless steel and/or one of variousalloys of platinum are commonly used to make such coil springs for usein guidewires. Core wire 42 can be made from shape memory metal, such asnitinol, or preferably is a stainless steel wire tapered at the distalend. For treating small caliber vessels such as coronary arteries, corewire 42 will preferably measure about 0.006 inch (0.15 mm) in diameter.

Tubular shaft 44 is slidably disposed around core wire 42, and includesrelatively stiff proximal portion 46 and relatively flexible distalportion 48. Proximal portion 46 is preferably made from thin walledstainless steel tubing, usually referred to as hypotubing, althoughother metals can be used. Various metals or polymers can be used to makerelatively flexible distal portion 48, although it is preferably madefrom thermoset polyimide tubing, available from sources such as HVTechnologies, Inc., Trenton, Ga., U.S.A. The length of distal portion 48may be selected as appropriate for the intended use of the filterguidewire. In one example, portion 48 may be designed and intended to beflexible enough to negotiate tortuous coronary arteries, in which casethe length of portion 48 may be 15-35 cm (5.9-13.8 inches), preferablyat least approximately 25 cm (9.8 inches). In comparison to treatment ofcoronary vessels, adaptations of the invention for treatment of renalarteries may require a relatively shorter flexible portion 48, andversions intended for approaching vessels in the head and neck mayrequire a relatively longer flexible portion 48.

When filter guidewire 20 is designed for use in small vessels, shaft 44may have an outer diameter of about 0.014 inch (0.36 mm). The generaluniformity of the outer diameter is preferably maintained by connectingproximal portion 46 and distal portion 48 with lap joint 49. Lap joint49 uses any suitable adhesive, preferably cyanoacrylate instantadhesives from Loctite Corporation, Rocky Hill, Conn., U.S.A., or DymaxCorporation, Torrington, Conn., U.S.A. Lap joint 49 can be formed by anyconventional method such as reducing the wall thickness of proximalportion 46 in the region of joint 49, or by forming a step-down indiameter at this location with negligible change in wall thickness, asby swaging.

Expandable tubular filter 25 is positioned concentrically with core wire42, and is sized such that when it is fully deployed, as shown in FIGS.1 and 2, the outer perimeter of filter 25 will contact the inner surfaceof the vessel wall. The surface contact is preferably maintained aroundthe entire vessel lumen to prevent any emboli from slipping past filter25. Preferably, cyanoacrylate adhesive is used to secure filter distalend 27 to tip member 43, and to secure filter proximal end 29 near thedistal end of shaft 44. Optionally, radiopaque marker bands (not shown),such as platinum rings, can be incorporated into the adhesive jointssecuring filter ends 27, 29 respectively to tip member 43 and shaft 44.Filter 25 is deployed by advancing, or pushing shaft 44 relative to corewire 42 such that filter distal and proximal ends 27, 29 are drawntoward each other, forcing the middle, or central section of filter 25to expand radially. Filter 25 is collapsed by withdrawing, or pullingshaft 44 relative to core wire 42 such that filter distal and proximalends 27, 29 are drawn apart from each other, forcing the middle, orcentral section of filter 25 to contract radially.

Transition sleeve 45 is fixed about core wire 42 and is slidably locatedwithin the distal end of flexible distal portion 48 of tubular shaft 44.Transition sleeve 45 is preferably made of polyimide tubing similar tothat used in distal portion 48 and extends distally there from. Bypartially filling the annular space between core wire 42 and shaft 44,and by contributing additional stiffness over its length, sleeve 45supports core wire 42 and provides a gradual transition in overallstiffness of filter guidewire 20 adjacent the distal end of shaft 44.Transition sleeve 45 is fixed to core wire 42, preferably withcyanoacrylate adhesive, such that relative displacement between shaft 44and core wire 42 causes corresponding relative displacement betweenshaft 44 and sleeve 45. The length and mounting position of sleeve 45are selected such that sleeve 45 spans the distal end of shaft 44regardless of the configuration of filter 25 and the correspondingposition of shaft 44 relative to core wire 42. When constructed asdescribed above, filter guidewire 20 provides the functions of atemporary filter combined with the performance of a steerable guidewire.

FIG. 6 depicts a second embodiment of the invention in which filterguidewire 51 incorporates a typical steerable guidewire 55 and deploys aself-expanding filter. Guidewire 55 comprises core wire 52, including atapered distal end, and flexible tubular tip member 54, which ispreferably a coiled spring, fixed there around. At least a distalportion of tip member 54 is preferably made from radiopaque metal wire,such as an alloy of platinum. Self-expanding filter 25 is mounted aboutguidewire 55, with filter distal and proximal ends 27, 29 being mountedslidably there along and, optionally, being fitted with radiopaquemarkers (not shown). Filter proximal end 29 is attached to actuator 63,typically using adhesive or solder. Actuator 63 is mounted slidablyabout guidewire 55 and is preferably made of shape memory metal, such asnitinol. Actuator 63 is illustrated in FIG. 7, with alternativeactuators 163, 263 and 363 depicted in FIGS. 8, 9 and 10, respectively.In actuator 163, a series of ridges having increasing diameters presentstapered surface 164 for step-wise engagement with rod distal end 82.Actuator 263 provides a single ridge 264 for engagement with rod distalend 82. Rod distal end 82 can be formed with a complementary recess (notshown) to mate with ridge 264 for a snap-fit type engagement there with.In actuator 363, a series of barbs having increasing diameters presentstapered surface 364 for step-wise engagement with rod distal end 82. Avariety of other designs for mating components can be applied to theinvention to detachably join rod distal end 82 and actuator 63. Examplesinclude male and female screw threads, hook and loop elements common inthe field of textiles, or numerous mechanisms intended to temporarilyjoin extension wires to guidewires, examples of which are shown in U.S.Pat. No. 4,827,941 (Taylor), U.S. Pat. No. 5,113,872 (Jahrmarkt et al.)and U.S. Pat. No. 5,133,364 (Palermo et al.).

Stop element 77 is preferably a polyimide tube or ring that is fixedabout guidewire 55 at a location between filter distal end 27 and filterproximal end 29. This embodiment may include assist spring 95, which ispreferably a coiled tension spring mounted around guidewire 55 insidefilter 25, and having distal and proximal ends fixed to filter distaland proximal ends 27, 29, respectively. Spring 95 can assist in thedeployment of filter 25 by providing tension between filter distal andproximal ends 27, 29. Spring 95 can be mounted around stop element 77,or spring 95 may have some turns of the coil attached directly toguidewire 55 such that spring 95 can replace stop element 77. Elongatehollow rod 80 is slidably and removably disposed along guidewire 55 suchthat rod distal end 82 is engageable with actuator 63, as shown in thealternate position in FIG. 6. Rod 80 can be made from metal such asstainless steel or nitinol, or preferably from a rigid polymer such aspolyimide.

FIG. 11 illustrates a third embodiment of the invention in which filterguidewire 50 also incorporates steerable guidewire 55, as describedabove with respect to filter guidewire 51. In filter guidewire 50, themounting arrangement of filter 25 is reversed with respect to filterguidewire 20, such that filter distal end 27 is slidably mounted aroundand adjacent to the distal end of guidewire 55, and filter proximal end29 is fixed to guidewire 55. Elongate tubular actuator 60 is slidinglyand coaxially disposed around guidewire 55 proximal to filter 25. Link65 movably extends through opening 66 in filter 25 adjacent filterproximal end 29 and connects the distal end of actuator 60 to filterdistal end 27. Opening 66 is one of the inlet openings of filter 25,however any opening large enough to slidably pass link 65 will suffice.For example, a standard or over-sized pore in filter 25 may permit link65 to extend there through. Actuator 60 can be made from thin walledmetal tubing, such as stainless steel hypodermic tubing, or morepreferably, polyimide tubing. When an embodiment of filter guidewire 50is designed and intended for use in clinical applications withsmall-lumen catheters, such as PTCA catheters, then actuator 60 shouldhave an outside diameter of 0.014 inch (0.36 mm) or less so that filterguidewire 50 can be slidably received within the guidewire lumen of thecatheter. Link 65 is preferably a thin wire, such as stainless steel,measuring approximately 0.002 to 0.008 inch (0.05 to 0.20 mm) indiameter, most preferably 0.006 inch (0.15 mm). Alternatively, link 65may be a non-metallic filament capable of pushing and/or pulling filterdistal end 27.

Transformation of filter 25 from the deployed configuration to thecollapsed configuration, shown in FIG. 14, is achieved by manipulatingthe proximal ends of guidewire 55 and actuator 60 as follows. Pushingactuator 60 distally while pulling guidewire 55 proximally causes link65 to advance into filter 25 and displace filter distal end 27 distallyalong guidewire 55. The movement of filter distal end 27 away fromfilter proximal end 29, which is fixed to guidewire 55, forces filter 25to collapse around guidewire 55 to a lower profile that is suitable forintroduction to or withdrawal from the patient. The distal end ofactuator 60 is spaced proximally from filter proximal end 29 a distancesufficient to permit a range of motion of actuator 60 without contactingfilter proximal end 29. In this first version of the third embodiment ofthe invention, wherein filter 25 is self-expanding, link 65 is placedunder compression loading to collapse filter 25, and thus link 65 isalso referred to as a push rod.

Optionally, filter 25 may be self-collapsing, wherein its shape memoryis to return to the collapsed configuration. In this second version ofthe third embodiment of the invention, deployment of filter 25 isachieved and maintained by pulling actuator 60 proximally while pushingguidewire 55 distally, which action draws filter distal end 27 andfilter proximal end 29 towards each other and forces expansion of filter25. In this embodiment, link 65 is placed under tension loading todeploy filter 25.

In the development of temporary guidewire filters, it has beendetermined that there may be practitioners who habitually tend to pushthe outer rod and pull the core wire when attempting to collapse thefilter, which is contrary to the motion required in the conventionalarrangements shown in FIGS. 3 and 4 and also in FIG. 5. Thus, the“reverse” push-pull action required in the self-expanding version offilter guidewire 50 is a more natural motion for a number of users.

FIG. 12 depicts filter guidewire 56, which is a fourth embodiment of theinvention, and wherein self-expanding filter 25 is arranged overguidewire 55 similarly to filter guidewire 50, described above. Infilter guidewire 56, actuator 62 is a short ring slidingly and coaxiallydisposed around guidewire 55 proximal to filter 25. Link 70 movablyextends through opening 78 within filter proximal end 29 and connectsactuator 62 to filter distal end 27. Link 70 includes link proximalsegment 72 and link distal segment 74. Link distal segment 74 is atubular element that is fixed to filter distal end 27 and is slidinglydisposed around guidewire 55 within filter 25. Link distal segment 74 ismade from thin walled tubing, preferably polyimide. Link proximalsegment 72 is comparable to the wire of link 65, and extends from anattachment point on actuator 62 into filter 25 to connect with linkdistal segment 74. Joint 76 attaches filter proximal end 29 to guidewire55, and includes opening 78, which guides link proximal segment 72 whichis slidably disposed there through. Joint 76 may be made from anysuitable fastening material such as adhesive, braze alloy, orpreferably, solder. Preferably, opening 78 is formed by a short sectionof thin walled polyimide tubing (not shown), which is incorporated intojoint 76 within filter proximal end 29. Alternatively, opening 78 can beformed by including a removable mandrel, such as a stainless steel wirecoated with polytetrafluoroethylene (PTFE), in joint 76 during itsformation. The fastening material of joint 76 will not adhere to themandrel, which can be removed to leave opening 78.

Elongate hollow rod 180 is slidably and removably disposed alongguidewire 55 such that rod distal end 182 is engageable with actuator62. Rod distal end 182 is an over-sized section of rod 180 such that itwill slidably fit over at least a proximal portion of actuator 62, asshown in the alternate position in FIG. 12. The engaged combination ofrod 180 and actuator 62 can apply distally directed force to link 70,similarly to the operation of elongate actuator 60 in guidewire filter50. Thus, pushing rod 180 distally while pulling guidewire 55 proximallycauses link 70 to advance into filter 25 and translate filter distal end27 along guidewire 55 in a distal direction. The movement of filterdistal end 27 away from filter proximal end 29, which is fixed toguidewire 55, forces filter 25 to collapse around guidewire 55 to alower profile for introduction to or withdrawal from the patient.Actuator 62 is spaced proximally from filter proximal end 29 a distancesufficient to permit a range of motion of actuator 62 without contactingfilter proximal end 29. Optionally, rod distal end 182 can be anunexpanded end of rod 180, similar to rod distal end 82 of rod 80, inwhich case rod distal end 182 may simply abut actuator 62 withoutextending there over.

Optional stop 79, preferably a ring, may be fixed to guidewire 55proximal to actuator 62. Stop 79 can prevent interventional catheterspositioned on guidewire 55 from engaging and moving actuator 62 andunintentionally collapsing filter 25. Stop 79 is smaller in diameterthan actuator 62 such that rod 180 may be sized to slide over stop 79and engage actuator 62, as shown in the alternate position in FIG. 12.

There are advantages to filter guidewire 56, besides the more habitual“reverse” push-pull action that it shares with filter guidewire 50,described above. In filter guidewire 50, guidewire 55 must be smallenough to fit slidably inside of actuator 60 which, in turn, must fitinside the guidewire lumen of a therapeutic catheter. In filterguidewire 56, guidewire 55 can be large enough to fill the guidewirelumen of the same sized therapeutic catheter, because elongate rod 180can be removed and replaced with the catheter. Thus, a larger, morestandard sized guidewire can be included in the filter device, with theattendant performance advantages that accompany such an increase insize.

As an alternative to the arrangements shown in FIGS. 6 and 12, it may bedesirable to use a catheter, such as catheter 10, to operate actuators63, 62 of guidewire filters 51, 56 respectively, to collapseself-expanding filter 25. In such an arrangement, catheter 10 replacesrods 80, 180 in all respects, and no exchange is required there between.This simplified method of use can be performed during filter placement,during withdrawal, or during both steps. FIG. 13 shows catheter 10placed over filter guidewire 56, with optional stop 79 omitted therefrom. FIG. 14 shows the same arrangement as FIG. 13, with catheter 10being advanced to operate actuator 62, causing filter 25 to collapse. Asshown in FIG. 14, balloon 11 of catheter 10 would typically be deflatedwhile catheter 10 is used to collapse filter 25.

FIG. 15 depicts filter guidewire 85, which is a modification of filterguidewires 50, 56, and is made by mounting proximal assist spring 87around guidewire 55 between filter proximal end 29 and actuators 60, 62.A modification of filter guidewire 56, filter 25 is self-expanding, andspring 87 is a coiled compression spring that assists in the expansionof filter 25 by maintaining a separating force between filter proximalend 29 and actuator 62. Spring 87 can surround guidewire 55 only or,preferably, spring 87 surrounds both guidewire 55 and link 65, 70, asshown. Alternatively, in a modification of filter guidewire 50, filter25 is self-collapsing, with spring 87 being a coiled tension springattached at its ends to filter proximal end 29 and actuator 60. Todeploy such a self-collapsing version of filter 25, actuator 60 canapply proximally directed force to overcome the shape memory of filter25 and the tension force in spring 87.

FIG. 16 depicts filter guidewire 89, which is another modification tofilter guidewires 50, 56, and is made by mounting assist spring 91around guidewire 55 distal to filter 25. In the modification of filterguidewire 56, filter 25 is self-expanding, with spring 91 being a coiledcompression spring having a proximal end abutting filter distal end 27and having a distal end fixed to guidewire 55. Spring 91 assists in thedeployment of filter 25 by maintaining proximally directed force againstfilter distal end 27. Alternatively, in a modification of filterguidewire 50, filter 25 is self-collapsing, with spring 91 being atension spring having a proximal end fixed to filter distal end 27 andhaving a distal end fixed to guidewire 55. To deploy such aself-collapsing version of filter 25, actuator 60 can apply proximallydirected force to overcome the shape memory of filter 25 and the tensionforce in spring 91.

FIG. 17 depicts filter guidewire 93, which is another modification tofilter guidewires 50, 56, and is made by mounting assist spring 95around guidewire 55 and link distal segment 74 inside filter 25. In themodification of filter guidewire 56, filter 25 is self-expanding, withspring 95 being a coiled tension spring having a distal end attached tofilter distal end 27 and having a proximal end attached to filterproximal end 29. Spring 95 assists in the deployment of filter 25 bymaintaining tension between filter distal and proximal ends 27, 29.Alternatively, in a modification of filter guidewire 50, filter 25 isself-collapsing, with spring 95 being a coiled compression springmounted between filter distal and proximal ends 27, 29. To deploy such aself-collapsing version of filter 25, actuator 60 can apply proximallydirected force to overcome the shape memory of filter 25 and thecompression force in spring 95. All of the above-mentioned coiled assistsprings can be fabricated with fine metal wire of about 0.001 to 0.005inch (0.03 to 0.13 mm) diameter, preferably nitinol wire having 0.003inch (0.08 mm) diameter.

To adjust and maintain the relative longitudinal and/or rotationalpositions of guidewires and the surrounding tubular elements in thevarious embodiments of the invention, a removable handle device (notshown) of a type familiar to those of skill in the art may be used. Suchhandle devices can have telescoping shafts with collet-type clamps thatgrip respectively, core wire 42 and shaft 44 in filter guidewire 20,guidewire 55 and actuator 60 in filter guidewire 50, and guidewire 55and rods 80, 180 in filter guidewires 51 and 56. The handle device canalso serve as a steering handle, or “torquer” which is useful forrotating steerable-type guidewires that are incorporated in the instantinvention.

The methods of using of the filter guidewires of the invention will bedescribed below. Referring to FIG. 18, filter guidewire 85, havingself-expanding filter 25 and actuator 62, is provided (step 100), andfilter 25 is collapsed by advancing hollow rod 80 against actuator 62(step 102). With filter 25 in the collapsed configuration, filterguidewire 85 is advanced into the patient's vasculature until filter 25is beyond the intended treatment site (step 104). Withdrawal of rod 80allows filter 25 to expand under the combination of its own shape memoryand the compression force of proximal spring 87 (step 106). With filter25 deployed into contact with the vessel wall, a therapeutic catheter isadvanced over filter guidewire 85 to the intended treatment site (step108), and the therapy, such as balloon angioplasty, is performed (step110). Any embolic debris generated during the therapy is captured infilter 25. After the therapy is completed, the therapeutic catheter isprepared for withdrawal, as by deflating the balloon, if so equipped,and the catheter is advanced against actuator 62 to cause filter 25 tocollapse (step 112). Finally, while the catheter is used to continuouslyapply distally directed force against actuator 62 to maintain filter 25in its collapsed configuration, filter guidewire 85 and the therapeuticcatheter can be withdrawn together (step 114). Although the steps abovedescribe using rod 80 and the therapeutic catheter to introduce andwithdraw filter guidewire 56, respectively, it should be understood thatvariations are possible, since any tubular device that can engage andoperate actuator 62 can be used, either during introduction orwithdrawal.

During use of filter guidewire 51, as shown in FIG. 20, rod 80 is firstadvanced over guidewire 55 until it engages actuator 63 (step 202).Pulling guidewire 55 proximally while pushing rod 80 distally againstactuator 63 forces actuator 63 to slide distally until it is restrainedby stop element 77. With actuator 63 thus restrained, rod 80 can attaina secure, albeit temporary, engagement with actuator 63 by wedging roddistal end 82 onto proximal taper 64 of actuator 63. To collapse filter25, forces are applied to separate filter distal and proximal ends 27,29. Proximally directed force is applied to filter proximal end 29 bypulling the engaged combination of rod 80 and actuator 63 proximally.Simultaneously, distally directed force is applied to filter distal end27 by pushing guidewire 55 distally, which advances stop element 77 intocontact with filter distal end 27. Applying a first degree of proximallydirected force to rod 80 will cause filter 25 to collapse (step 204),such that filter guidewire 51 can be introduced into the patient anddirected to the desired treatment site (step 206).

Once filter guidewire 51 has reached the intended location, applying asecond, higher degree of proximally directed force to rod 80 willdisengage rod 80 from actuator 63 (step 208). With rod 80 and actuator63 thus disengaged, rod 80 can be withdrawn from the patient and filter25 is free to expand under its mechanical memory, optionally assisted byspring 95. Once filter 25 has expanded to cover the lumen of the vesseldistal to the treatment area, therapeutic catheter 10 is advanced overfilter guidewire 51 (step 210) and the desired therapy is implemented(step 212). Upon completion of the treatment, catheter 10 is removedfrom filter guidewire 51 and is replaced with rod 80. Rod 80 is againengaged with actuator 63, as described above, to provide a first degreeof proximally directed force for collapsing filter 25 and permittingwithdrawal of filter guidewire 51 from the patient.

Filter guidewires 51, 56, as described above, utilize removable hollowrods 80, 180, respectively, to engage and manipulate actuators 63, 62,respectively. FIG. 19 depicts a rapidly exchangeable rod 280 for usewith filter guidewires 51, 56. Rod 280 includes proximal shaft 284, anddistal section 286, which is essentially a short portion of rods 80,180. Distal section 286 is only about 10-30 cm (3.9-11.8 inches) long,making it easy to exchange over the portion of filter guidewire 51, 56that extends outside of the patient, as is understood by those of skillin the field of intravascular catheters. Proximal shaft 284 preferablyis a wire having a minimum diameter of about 0.012 inch (0.30 mm), andis tapered and attached to distal section 286. The stiffness of proximalshaft 284, and the secure attachment thereof to distal section 286provide a rapidly exchangeable alternative to rods 80, 180 for pushingor pulling actions, as may be required. It will be understood thatcatheter 10 can also be of the rapid exchange type to facilitateinterchanging rods and catheters.

FIG. 24 depicts filter guidewire 150, a fifth embodiment of theinvention. Filter guidewire 150 incorporates filter 25 and link 65 fromfilter guidewire 50, actuator 62 with hollow rod 180 from filterguidewire 56, and proximal assist spring 87 from filter guidewire 85. Ina structure similar to these other embodiments, actuator 62 is slidinglydisposed about the guidewire, and link 65 extends through opening 78 toconnect actuator 62 to filter distal end 27. Removable rod 180 abutsactuator 62 and can advance it against spring 87 to collapse filter 25.Unlike integral guidewire 55 of the prior embodiments of the invention,the guidewire of filter guidewire 150 comprises disconnected guidewireproximal and distal shafts 155, 157. Filter proximal end 29 is fixednear the distal end of proximal shaft 155 and filter distal end 27 isfixed near the proximal end of distal shaft 157. As shown in FIG. 24,more than one link 65 may be desirable in bridging the gap betweenproximal and distal shafts 155, 157. As filter ends 27, 29 separate,links 65 are drawn into filter 25 through openings 78. The combinationof filter 25 and multiple links 65 can provide a relatively uniformtransition from proximal shaft 155 to distal shaft 157.

One benefit of the structure of filter guidewire 150 is that guidewiredistal shaft 157 extending from filter distal end 27 forms a fixedlength tip of the device, regardless of the configuration of filter 25.Conversely, in filter guidewire 56, the tip length changes as filterdistal end 27 slides along guidewire 55 during transformation of filter25 between open and collapsed configurations. The variable tip length offilter guidewire 56 provides a short tip when filter 25 is collapsed, asduring advancement of filter 25 to treatment area 15, but the tip needsto lengthen distally of treatment area 15, if possible, duringdeployment of filter 25. During deployment of improved filter guidewire150, the distal tip position of the device remains fixed relative to thetreatment area. This is accomplished by the user holding rod 180anchored relative to the patient, while applying tension to proximalshaft 155 in the proximal direction. The fixed position of rod 180 canhold actuator 62, link 65 and thus, filter distal end 27 stationarydistally adjacent treatment area 15. Meanwhile, filter 25 can bemaintained in a collapsed configuration by the proximal tension appliedto proximal shaft 155, thus holding filter proximal end 29 away fromfilter distal end 27. Releasing the tension on proximal shaft 155 allowsfilter 25 to expand by filter proximal end 29 advancing distally towardsfilter distal end 27. During this filter deployment, however, the distaltip does not need to move relative to filter 25 or treatment area 15.

FIG. 25 depicts filter guidewire 256, which is an alternative version ofthe fifth embodiment of the invention. Filter guidewire 256 incorporatesfilter 25, actuator 62, link 70 and removable hollow rod 180 (not shown)from filter guidewire 56, and proximal assist spring 87 from filterguidewire 85. Actuator 62 is slidingly disposed about guidewire proximalshaft 256, and link 70 extends through opening 78 to connect actuator 62to filter distal end 27. Rod 80 abuts actuator 62 and can advance itagainst spring 87 to collapse filter 25. This version slidingly joinsthe guidewire proximal and distal shafts within filter 25. Link 70includes link proximal segment 72 and link distal segment 74. Linkdistal segment 74 is a tubular element that is fixed to filter distalend 27 and guidewire distal shaft 257. Within filter 25, link distalsegment 74 is slidingly disposed around the distal end of guidewireproximal shaft 255, which preferably has a stepped-down diameter. Thisalternative version maintains the beneficial fixed-length tip of thefifth embodiment of the invention.

FIG. 26 depicts filter guidewire 356, which is another version of thefifth embodiment of the invention. Filter guidewire 356 incorporatesfilter 25, link 65 from filter guidewire 50, actuator 62 and hollow rod180 (not shown) from filter guidewire 56, and proximal assist spring 87from filter guidewire 85. In a structure similar to these other versionsof the fifth embodiment of the invention, actuator 62 is slidinglydisposed about the guidewire, and link 65 extends through opening 78 toconnect actuator 62 to filter distal end 27. Removable rod 180 (notshown) abuts actuator 62 and can advance it against spring 87 tocollapse filter 25. As distinguished from filter guidewire 256, thesliding connection between proximal and distal guidewire shafts in thisversion comprises tubular segment 374 and distal core segment 353.Tubular segment 374 is fixed to, and extends distally from proximalshaft 355, which is preferably stepped-down in diameter at distal end352. Distal core segment 353 extends proximally from tubular tip member354 of distal guidewire shaft 357, and is slidingly disposed withintubular segment 374. As filter ends 27, 29 separate, distal core segment353 is partially withdrawn distally from tubular segment 374. Tubularsegment 374 may be any suitable thin-walled material, such as polyimide,or preferably nitinol. Distal core segment 353 may be tapered to avoidabrupt transitions in stiffness, especially adjacent the distal end oftubular segment 374. This second alternative version maintains thebeneficial fixed-length tip of the fifth embodiment of the invention.

In the second embodiment of the invention, depicted in FIG. 6 as filterguidewire 51, and in its alternative versions described below, thelength of the guidewire tip distal to filter distal end 27 may vary, butnot in direct response to transformation of filter 25 between collapsedand open configurations. Both filter ends 27, 29 are free to slide alongthe guidewire, limited by stop element 77, which is fixed to theguidewire within filter 25. When actuator 63 is engaged with hollow rod80, and proximal tension is applied to these combined elements, thenfilter distal end 27 is drawn against stop element 77, maximizing thelength of the guidewire tip. When filter 25 is permitted to open itselfby the disengagement of actuator 63 from rod 80, filter proximal end 29advances distally and filter distal end 27 may or may not shorten thelength of the guidewire tip by moving distally. To the extent that theguidewire tip length remains relatively fixed, this second embodiment ofthe invention also exhibits the advantages of the fixed-length tip ofthe above-mentioned fifth embodiment of the invention.

There is a concern that, in the second embodiment of the invention,filter 25 may expand itself too quickly when actuator 63 is releasedfrom its engagement with rod 80, causing filter 25 to abruptly strikethe vessel wall, perhaps resulting in tissue injury. The followingalternative versions of the second embodiment include mechanisms fordamping the movement of actuator 63, and thus slowing the deployment offilter 25.

FIG. 27 depicts filter guidewire 151, which is an alternative version ofthe second embodiment of the invention, shown in FIG. 6 as filterguidewire 51. Filter guidewire 151 incorporates the same structure andcomponents as filter guidewire 51, except that actuator 463 is,optionally, longer than actuator 63, and visco-elastic damping gel 90 isapplied around guidewire 55. As described above (see paragraph 0053),applying a sufficient degree of proximally directed force to rod 80 willdisengage rod 80 from actuator 463, thus freeing filter 25 to expandunder its mechanical memory. To slow deployment of filter 25, dampinggel 90 applies drag to the sliding movement of actuator 463 alongguidewire 55. Gel 90 can be applied to guidewire 55, over the sectionthereof that actuator 463 will move along or, optionally, gel 90 can beapplied to the lumen of actuator 463. Gel 90 may be a biocompatiblegrease-like substance, such as a silicone gel. Actuator 463 ispreferably longer than actuator 63 to provide a greater luminal surfacearea for better damping. Visco-elastic damping gel 90 is preferred to amechanical friction mechanism because the latter structure couldprematurely stop the sliding movement of actuator 463, possiblypreventing filter 25 from expanding fully into contact with the vesselwall.

FIG. 28 depicts filter guidewire 251, which is another alternativeversion of the second embodiment of the invention, shown in FIG. 6 asfilter guidewire 51. Filter guidewire 251 incorporates the samestructure and components as filter guidewire 51, except that actuator563 incorporates hydrodynamic drag scoop 190 to slow deployment offilter 25, similarly to the function of damping gel 90 in filterguidewire 151 above. Drag scoop 190 comprises a funnel at the distal endand may be formed integrally with actuator 563, or it may be a separatecomponent fixed thereto. Filter proximal end 29 may be attached toactuator 563 adjacent the engageable portion or it may be attachedadjacent the distal funnel of drag scoop 190, as shown in FIG. 28. Dragscoop 190 and the funnel at its distal end can be made of polymericmaterials or metals, such as stainless steel or nitinol. To prevent thefunnel from increasing the collapsed profile of filter 25 too much, thefunnel can comprise self-expanding, overlapping petals (not shown),which can collapse closely around guidewire 55.

Drag scoop 190 applies drag to the sliding movement of actuator 563along guidewire 55. The annular space between drag scoop 190 andguidewire 55 is preferably a small clearance, such as about 0.002-0.005inch (0.05-0.13 mm), which fills with vessel fluid, such as blood. Whenactuator 563 is released from rod 80 and begins to move distally, asshown by arrows 193, the funnel at the distal end collects fluid andforces it into the annular space, as shown by arrows 195. The excessiveamount of fluid forced into the annular space causes hydrodynamic dragon actuator 563, slowing the deployment of filter 25.

FIG. 29 depicts filter guidewire 351, which is yet another alternativeversion of the second embodiment of the invention, shown in FIG. 6 asfilter guidewire 51. Filter guidewire 351 incorporates the samestructure and components as filter guidewire 51, except that vacuumapparatus 290 (shown schematically) applies a partial vacuum betweenhollow rod 80 and guidewire 55 to form the attachment between rod distalend 82 and actuator 63. By slowly releasing the partial vacuum appliedby apparatus 290, actuator 63 can be slowly released from its attachmentto rod distal end 82, thus slowing the deployment of filter 25. Actuator63 may have an optional tubular extension (not shown) protrudingproximally within rod 80. The tubular extension can reduce the annulusbetween hollow rod 80 and guidewire 55, further slowing thedisengagement of actuator 63 from rod 80 when the vacuum is released.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and detail may bemade there in without departing from the spirit and scope of theinvention. For example, the invention may be used in any intravasculartreatment utilizing a guidewire where the possibility of looseningemboli may occur. Although the description herein illustratesangioplasty and stent placement procedures as significant applications,it should be understood that the present invention is in no way limitedto those environments.

We claim:
 1. A temporary filter device comprising: an elongate proximalguidewire shaft having a distal end; a relatively short distal guidewireshaft having a proximal end and being disposed distal to and coaxiallyaligned with the proximal shaft; a generally tubular filter mountedcoaxially about the proximal and distal guidewire shafts, the filterhaving a tapered distal end fixed adjacent the proximal end of thedistal shaft and a tapered proximal end fixed adjacent the distal end ofthe proximal shaft, wherein relative longitudinal movement between thedistal and proximal ends of the filter accompanies a transformation ofthe filter between a collapsed configuration and an open configuration;an actuator slidably disposed along the proximal guidewire shaft; and atleast one link slidably disposed through at least one opening near thefilter proximal end and connecting the actuator to the distal end of thefilter.
 2. The temporary filter device of claim 1 wherein the at leastone link includes a tubular distal segment slidably disposed about thedistal end of the proximal guidewire shaft, the tubular distal segmentbeing disposed within the filter.
 3. The temporary filter device ofclaim 1 wherein the distal end of the proximal guidewire shaft isreduced in diameter.
 4. The temporary filter device of claim 1 whereinthe proximal end of the filter is fixed about the proximal guidewireshaft by a joint having the at least one opening there through.
 5. Thetemporary filter device of claim 1 wherein a flexible tubular element isfixed about the distal guidewire shaft.
 6. The temporary filter deviceof claim 1 wherein the actuator is an elongate tube.
 7. The temporaryfilter device of claim 1 wherein the actuator is a relatively short tubeor ring.
 8. The temporary filter device of claim 7 further comprising anelongate hollow rod slidably disposed along the proximal guidewireshaft, the rod having a distal end engageable with the actuator.
 9. Thetemporary filter device of claim 7 further comprising a coiledcompression spring disposed around the proximal guidewire shaft betweenthe actuator and the proximal end of the filter to assist in thetransformation of the filter to the open configuration.
 10. A temporaryfilter device comprising: an elongate proximal core wire having a distalend; a distal core wire having a proximal portion, the distal core wirebeing disposed distal to and coaxially aligned with the proximal corewire; a tubular segment having a distal end, the tubular segment beingfixedly disposed about the distal end of the proximal core wire andextending distally there from to slidably engage the proximal portion ofthe distal core wire; a generally tubular filter mounted about thedistal core wire and the tubular segment, the filter having a tapereddistal end fixed to the distal core wire and a tapered proximal endfixed to the tubular segment, wherein relative longitudinal movementbetween the distal and proximal ends of the filter accompanies atransformation of the filter between a collapsed configuration and anopen configuration; an actuator slidably disposed along the proximalcore wire proximally of the filter; and a link slidably disposed throughan opening near the filter proximal end and connecting the actuator tothe distal end of the filter.
 11. The temporary filter device of claim10 wherein the distal end of the proximal core wire is reduced indiameter.
 12. The temporary filter device of claim 10 wherein theproximal end of the filter is fixed about the tubular segment by a jointhaving the opening there through.
 13. The temporary filter device ofclaim 10 wherein a flexible tubular element is fixed about the distalcore wire.
 14. The temporary filter device of claim 10 wherein theactuator is an elongate tube.
 15. The temporary filter device of claim10 wherein the actuator is a relatively short tube or ring.
 16. Thetemporary filter device of claim 15 further comprising an elongatehollow rod slidably disposed along the proximal core wire, the hollowrod having a distal end engageable with the actuator.
 17. The temporaryfilter device of claim 16 further comprising a coiled compression springdisposed around the proximal core wire between the actuator and theproximal end of the filter to assist in the transformation of the filterto the open configuration.